Embodiments of the present invention relate to a radio communication device having at least one printed circuit board of specified length and a specified transverse dimension accommodated in a housing and having at least one antenna, coupled to said printed circuit board, for emitting and/or receiving electromagnetic radio fields.
Through the emission of energy from radio communication devices, a certain portion of the electromagnetic radio fields is usually also radiated into the human body. This is particularly true in cases of mobile radio devices and cordless telephones such as, for example, those conforming to the DECT (Digital Enhanced Cordless Telecommunications) standard. Organic tissue in a user's head can in particular be exposed to impermissibly high levels of radio fields when the radio communication device is placed next to it. Limiting values for thermal energy absorption have consequently been specified for human organic tissue. What is termed the SAR (“Specific Absorption Rate”) rating is used as a criterion for measuring the radiation load to which respective users are actually exposed. This rating indicates in watts per kilogram the specific absorption rate at which a pre-definable area of tissue volume is heated.
An exemplary embodiment of the invention describes a radio communication device to be set in a better controlled manner in terms of its electromagnetic radiation characteristics. A radio communication device is coupled to at least one additional, electrically conductive correction element via a printed circuit board wherein a targeted, fictive current-path elongation is produced for electric current induced by electromagnetic radio fields of the antenna. Under the exemplary configuration, the pre-defined longitudinal and transverse dimensions of the printed circuit board are substantially retained.
The local distribution of the resulting electric current on the printed circuit board can in this way be better set in a targeted, (i.e., controllable) manner.
The current-path elongation effected on the printed circuit board with the aid of the additional, electrically conductive correction element makes it possible to influence the local current distribution there in such a manner that any present local maximum of the electric current or, as the case may be, of a magnetic field associated with said current, can be displaced into a less critical area of the device and/or reduced. It further makes it possible to reduce or even substantially avoid impermissibly intense “hotspots”, where areas of tissue volume having higher SAR values compared to such areas having lower SAR values, and hence reduce or even substantially avoid local variations in the thermal loading of areas of tissue volume—such as, for example, in the area of the respective user's head. By means of at least one such additional correction element, the SAR distribution can, viewed overall, be made at least more even or, as the case may be, more homogeneous compared to the SAR distribution of the same printed circuit board not having a correction element. Improved antenna impedance matching of the respective radio communication device and hence improved energy emission can, moreover, be advantageously achieved, which is favorable in particular when device dimensions are small with the device being relatively compact in design.
Other exemplary embodiments are described in the figures and text that appear below.